层数最深叶子节点的和

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1302. 层数最深叶子节点的和 - 力扣（LeetCode）

给你一棵二叉树的根节点 root ，请你返回 层数最深的叶子节点的和 。

示例 1：

输入： root = [1,2,3,4,5,null,6,7,null,null,null,null,8]
输出： 15

示例 2：

输入： root = [6,7,8,2,7,1,3,9,null,1,4,null,null,null,5]
输出： 19

提示：

• 树中节点数目在范围 [1, 10^4] 之间。
• 1 <= Node.val <= 100

解题一

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number}
 */
var deepestLeavesSum = function (root) {
  let nodes = [root];
  while (true) {
    let children = [];
    for (let i = 0; i < nodes.length; i++) {
      if (nodes[i].left) {
        children.push(nodes[i].left);
      }
      if (nodes[i].right) {
        children.push(nodes[i].right);
      }
    }
    if (children.length) {
      nodes = children;
    } else {
      break;
    }
  }
  let sum = 0;
  for (let i = 0; i < nodes.length; i++) {
    sum += nodes[i].val;
  }
  return sum;
};

解题二

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number}
 */
var deepestLeavesSum = function (root) {
  let l = 0;
  let sum = 0;
  const dfs = (node, level) => {
    if (!node.left && !node.right) {
      if (level === l) {
        sum += node.val;
      } else if (level > l) {
        sum = node.val;
        l = level;
      }
    } else {
      if (node.left) {
        dfs(node.left, level + 1);
      }
      if (node.right) {
        dfs(node.right, level + 1);
      }
    }
  };
  dfs(root,0)
  return sum
};